Search results for "Geophysic"
showing 10 items of 2684 documents
Vineyard soil mapping from very high spatial resolution images in hillslope context: a contribution of terroir knowledge.
2014
The Burgundian vineyard hillslopes (Côte-d’Or, France) exhibit a high diversity of soils resulting from the combination of several natural and anthropogenic factors acting at various spatio-temporal scales. The soil types have major role in viticulture, since they partly determine wine-growing quality. However, soil undergoes important degradation caused by hydric erosion and vineyard management practices. To control this soil heritage for a sustained viticulture in Côte-d’Or, a better knowledge of soil is necessary. The objectives of this work is to characterise vineyard soils and to identify the factors governing their diversity using an interdisciplinary approach crossing geology, geomor…
The Coupled Magmatic and Hydrothermal Systems of the Restless Aluto Caldera, Ethiopia
2020
Seismicity can be used to better understand interactions between magma bodies, hydrothermal systems and their host rocks—key factors influencing volcanic unrest. Here, we use earthquake data to image, for the first time, the seismic velocity structure beneath Aluto, a deforming volcano in the Main Ethiopian Rift. Traveltime tomography is used to jointly relocate seismicity and image 3D P- and S-wave velocity structures and the ratio between them (V P/V S). At depths of 4–9 km, the seismicity maps the top of a large low velocity zone with high V P/V S, which we interpret as a more ductile and melt-bearing region. A shallow (<3 km) hydrothermal system exhibits low seismic velocities and ve…
Geochemical fingerprints of brannerite (UTi 2 O 6 ): an integrated study
2020
AbstractBrannerite (UTi2O6) is among the major uranium-bearing minerals found in ore deposits, however as it has been long considered as a refractory mineral for leaching it is currently disregarded in ore deposits. Brannerite is found in a variety of geological environments with the most common occurrences being hydrothermal and pegmatitic. On the basis of scanning electron microscopy observations coupled with electron probe micro-analyses and laser ablation inductively-coupled plasma mass spectrometer analyses, this study describes the morphological features and the major- and trace-element abundances of brannerite samples from five hydrothermal and five pegmatitic localities across the w…
The classification of submerged vegetation using hyperspectral MIVIS data
2009
The aim of this research is to use hyperspectral MIVIS data to map the Posidonia oceanica prairies in a coastal lagoon (Stagnone di Marsala). It is approximately 12 km long and 2 km wide and is linked to the open sea by two shallow openings. This environment is characterised by prairies of phanerogams, the most common of which is Posidonia oceanica, an ideal habitat for numerous species of fish, molluscs and crustaceans. A knowledge of the distribution of submerged vegetation is useful to monitor the health of the lagoon. In order to classify the MIVIS imagery, the attenuation effects of the water column have been removed from the signal using Lyzenga’s technique. A comparison between class…
In situ micro-Raman and X-ray diffraction study of diamonds and petrology of the new ureilite UAE 001 from the United Arab Emirates
2008
International audience; A new olivine-pigeonite ureilite containing abundant diamonds and graphite was found in the United Arab Emirates. This is the first report of a meteorite in this country. The sample is heavily altered, of medium shock level, and has a total weight of 155 g. Bulk rock, olivine (Fo79.8-81.8) and pyroxene (En73.9-75.2, Fs15.5-16.9, Wo8.8-9.5) compositions are typical of ureilites. Olivine rims are reduced with Fo increasing up to Fo96.1-96.8. Metal in these rims is completely altered to Fehydroxide during terrestrial weathering. We studied diamond and graphite using micro-Raman and in situ synchrotron X-ray diffraction. The main diamond Raman band (LO=TO mode at ~1332 c…
Approches quantitatives de la production de fer sur le site hallstattien de Bragny-sur-Saône (Saône-et-Loire)
2007
This study is based on an inventory of iron knives dated from the 8th to the 5th centuries BC and discovered in funerary and settlement sites in the South-West of France. The corpus consists of 608 artefacts. We established a typology allowing us to present a chronological and spatial distribution of each type. We then tried to determine the functions of the knives according to their type and their length. For those discovered in graves other objects in the grave assemblage were used as an additional criterion. When the funerary context was very clearly defined, we tried to determine the function, in the grave itself, of the knives.
Geophysical study of an landslide in northern Sicily
2002
The San Fratello area in the Nebrodi Mountains (northern Sicily) is a region of high instability. It has suffered many devastating occurrences, which have hit and destroyed the village of San Fratello. At present the area is still subject to a high landslide risk. A series of geophysical surveys have been carried out with the aim of determining the thickness and dimensions of the landslide body as well as some tectonic features, in order to gain insight into the evolution of the landslide. The following geophysical techniques have been used: borehole seismic tomography, i.e. down-hole tomographic seismic soundings (DH TSS), time-domain electromagnetic (TDEM) soundings and georadar profiling…
Recognition of earthquake-induced damage in the Abakainon necropolis (NE Sicily): results from geo-morphological, geophysical and numerical analyses
2017
Seismotectonic activity and slope instability are a permanent threat in the archaeological site of Abakainon and in the nearby village of Tripi in NE Sicily. In recent times, signs of an ancient earthquake have been identified in the necropolis of Abakainon which dating was ascertained to the first century AD earthquake. The site is located on a slope of Peloritani Mts. along the Tindari Fault Line and contains evidence for earthquake-induced landslide, including fallen columns and blocks, horizontal shift and counter slope tilting of the tomb basements. In this paper, we used an integrated geomorphological and geophysical analysis to constrain the landslide. The research was directed to th…
Recurrence time distribution and temporal clustering properties of a cellular automaton modelling landslide events
2018
Abstract. Reasonable prediction of landslide occurrences in a given area requires the choice of an appropriate probability distribution of recurrence time intervals. Although landslides are widespread and frequent in many parts of the world, complete databases of landslide occurrences over large periods are missing and often such natural disasters are treated as processes uncorrelated in time and, therefore, Poisson distributed. In this paper, we examine the recurrence time statistics of landslide events simulated by a cellular automaton model that reproduces well the actual frequency-size statistics of landslide catalogues. The complex time series are analysed by varying both the threshold…
Integration of constrained electrical and seismic tomographies to study the landslide affecting the cathedral of Agrigento
2014
The Cathedral of Saint Gerland, located on the top of the hill of Agrigento, is an important historical church, which dates back to the Arab–Norman period (XI century). Unfortunately throughout its history the Cathedral and the adjacent famous Archaeological Park of the 'Valley of the Temples' have been affected by landslides. In this area the interleaving of calcarenites, silt, sand and clay is complicated by the presence of dislocated rock blocks and cavities and by a system of fractures partly filled with clay or water. Integrated geophysical surveys were carried out on the north side of the hill, on which the Cathedral of Agrigento is founded, to define lithological structures involved …